Covid Immune Response Faster and Stronger After Infection, Scientists Say | World news


Scientists have found the strongest evidence to date that people recovering from Covid can mount a much faster and more effective defense against infection if they encounter the virus again.Researchers at Rockefeller University in New York found that the immune system not only remembered the virus, but improved the quality of protective antibodies after an infection had passed, allowing the body to trigger a quick and powerful attack. if the virus invades a second time.

“This is very good news,” said Michel Nussenzweig, head of molecular immunology at Rockerfeller and lead author of the study. “People are expected to be able to produce a rapid antibody response and resist infection in a large number of cases.”

It’s unclear how long the immune system’s memory could last, but Nussenzweig said it could potentially provide some protection for years. The discovery may explain why re-infections verified by the virus have so far been quite rare.

When people are infected with coronavirus, the immune system launches a multi-pronged attack. One form of protection comes from T cells, which seek out and destroy infected cells and thus prevent the virus from spreading. A second front concerns the B cells, which release antibodies into the blood. The antibodies cling to the virus and prevent it from invading cells in the first place.

Once the infection has passed, the immune system retreats, but it remembers the virus by storing what are called memory T cells and memory B cells. If the virus returns, they are called upon to act immediately.

Numerous studies have shown that the first wave of antibodies to the coronavirus wanes after a few months, raising concerns that people are at risk of losing their immunity quickly. In their study of 87 coronavirus patients, the US researchers confirmed that antibodies were dropping, dropping to about a fifth of their peak level in six months, but that might not matter too much, they think. .

When the researchers looked at the memory of the immune system, they noticed that six months after infection, the antibodies produced by memory B cells had evolved to become more powerful. These highly sharpened antibodies could be released a few days after reinfection, rather than taking a few weeks to build up, as seen in primary infections.

Scientists then showed that tiny amounts of coronavirus, or protein fragments of inactive viral particles, lurk in patients’ intestines and apparently help maintain the memory of the immune system. The remains of the virus are not believed to be harmful.

“The lessons to be learned are that people who have been infected six months later have persistent B cell memory responses with antibodies that can neutralize the virus and may very well do so,” Nussenzweig said. This could mean eliminating the virus before it sets in, he added. “We don’t know how long protection will last, but it could be very long. It could take years.

The study is preliminary and has not been peer reviewed or published in a journal.

Charles Bangham, professor of immunology at Imperial College London, who was not involved in the study, said the work suggested that there was “a very good chance that if you are reexposed you will a stronger immune response ”to the virus. “It remains to be proven that it is protective, but you would be reasonably convinced that it would have a beneficial effect,” he said.

Arne Akbar, professor of immunology at University College London, said: “This is good news for everyone who has been diagnosed with coronavirus.” He said the immune system is like an army that retreats once the threat is over, but remains ready for a future invasion. “You want the army to be generated again very quickly, and that’s what these researchers found.”


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